Modular Infrared Heater with Nanofluid Thermal Accumulation Collector - Unsteady Entropy Analysis

The heating of a body (heat target, HT) by thermal radiation is often accompanied by heat losses, caused by the scattering of thermal rays and by not hitting its surface. These losses occur in infrared heating of different rooms. The heat source, i.e. modular infrared heater, can change the output intensity of thermal radiation within various wavelength intervals. Although there are different combinations of modular infrared heaters with variations in power, and geometric position in relation to HT, in this paper one characteristic combination, is analyzed. By setting the HT on the surface of the nanofluid collector with nano-enhanced phase change material (NePCM), it enables the increase in the overall efficiency of this heating process. The nanofluid collector consists of a complex pipe element through which the nanofluid flows, and a collector inside which the thermal-accumulating NePCM is placed. According to their characteristics, infrared thermal rays heat only HT, while the heating of the ambient air through which they pass is negligible. Based on this fact, the accumulated heat inside the NePCM can be used for convective heating of the ambient air around the HT surface. This process reduces the convective heat dissipation from HT to the ambient air and increases the efficiency of the modular infrared heat source. Furthermore, the accumulated heat inside the NePCM can be used for various technical applications. In this study, a mathematical model of the unsteady thermal entropy generation of the described heating system is established. By finding the unsteady thermal entropy, the next process of minimizing thermal irreversibility and maximizing the energy efficiency of the analyzed system is enabled. The volume fraction ratio of Al2O3 nanoparticles varies within the base fluid (water). Furthermore, the temperature of the infrared heaters varies as well as the volume fraction ratio of Al2O3 within the NePCM